Center for Outcomes Research and Epidemiology, College of Veterinary MediciMine, Kansas State University, Manhattan, Kansas, USA.
Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.
Foodborne Pathog Dis. 2024 Nov;21(11):698-707. doi: 10.1089/fpd.2024.0017. Epub 2024 Aug 2.
The study was conducted to determine the proportion and concentration of enterohemorrhagic (EHEC) O157 and six non-O157 (O26, O45, O103, O111, O121, and O145) serogroups and identify seasonal and processing plant differences in feces and on hides of cull dairy cattle processed in commercial slaughterhouses in the United States. Approximately 60 rectal and 60 hide-on samples from matched carcasses were collected in each of three processing plants, in two periods; summer of 2017 and spring of 2018. Samples before enrichment were spiral plated to quantify EHEC, and postenriched samples underwent culture methods that included immuno-magnetic separation, plating on selective media, and PCR assays for identification and serogroup confirmation of putative isolates. An isolate was considered EHEC O157 positive if it harbored serogroup-specific (), Shiga toxin (1 and/or 2), and intimin () genes and EHEC non-O157 positive if at least one of the non-O157 serogroup-specific, 1 and/or 2, and genes was identified. Generalized linear mixed models were fitted to estimate overall proportion of positives for EHEC O157 and non-O157 EHEC serogroups, as well as seasonal and processing plant differences in fecal and hide-on proportion of positives. The fecal EHEC proportion at the sample level was 1.8% (95% CI = 0.0-92.2%) and 4.2% (95% CI = 0.0-100.0%) for EHEC O157 and EHEC non-O157, respectively. Hide sample level proportion of positives was 3.0% (95% CI = 0.0-99.9%) for EHEC O157 and 1.6% (95% CI = 0.0-100.0%) for EHEC non-O157. The proportion of EHEC O157 and non-O157 significantly differed by processing plant and sample type (hide vs. feces), but not by season. The association between proportion of EHEC serogroups in feces with the proportion on hides collected from matched cattle was 7.8% (95% CI = 0.6-53.3%) and 3.8% (95% CI = 0.3-30.8%) for EHEC O157 and non-O157, respectively. Taken together, our findings provide evidence of a low proportion of EHEC serogroups in the feces and on hides of cull dairy cattle and that their proportion varies across processing plants.
本研究旨在确定美国商业屠宰场淘汰奶牛粪便和牛皮中肠出血性（EHEC）O157 血清群和六种非-O157（O26、O45、O103、O111、O121 和 O145）血清群的比例和浓度，并确定季节性和加工工厂差异。在三个加工工厂的每个工厂中，在两个时期（2017 年夏季和 2018 年春季）收集了大约 60 个直肠和 60 个皮-on 样本，来自匹配的胴体。在富集前，螺旋平板法用于定量 EHEC，富集后进行培养方法，包括免疫磁分离、选择性培养基平板培养和 PCR 检测，以鉴定和血清群确认疑似分离株。如果分离株携带血清群特异性（）、志贺毒素（1 和/或 2）和内膜蛋白（）基因，则认为是 EHEC O157 阳性，如果至少鉴定出一种非-O157 血清群特异性、1 和/或 2 和 基因，则认为是 EHEC 非-O157 阳性。采用广义线性混合模型估计 EHEC O157 和非-O157 EHEC 血清群的总体阳性比例，以及粪便和皮-on 阳性比例的季节性和加工工厂差异。在样本水平上，EHEC O157 和 EHEC 非-O157 的粪便 EHEC 比例分别为 1.8%（95%CI=0.0-92.2%）和 4.2%（95%CI=0.0-100.0%）。皮-on 样本水平的阳性比例分别为 EHEC O157 的 3.0%（95%CI=0.0-99.9%）和 EHEC 非-O157 的 1.6%（95%CI=0.0-100.0%）。EHEC O157 和非-O157 的比例因加工工厂和样本类型（皮-on 与粪便）而异，但不受季节影响。从匹配奶牛收集的粪便中 EHEC 血清群比例与皮-on 上收集的比例之间的关联分别为 EHEC O157 的 7.8%（95%CI=0.6-53.3%）和 EHEC 非-O157 的 3.8%（95%CI=0.3-30.8%）。总的来说，我们的研究结果提供了证据表明淘汰奶牛粪便和牛皮中 EHEC 血清群的比例较低，并且它们的比例在不同的加工工厂之间有所不同。
